Method of making molds for sound-records.



T. A. EDISON.

METHOD of MAKING MQLDS FOR soUNnRBcoRDs.

APPLICATION FILED JUNE 1o, 1911. 1,1 1 8, 1 14. Patented Nov. 24, 1914.

UNITED sTATEsrATENT oEEIcE.

THOMAS A. EDISON, OE LLEWELLYN PARK, WEsTonANGE, NEW JERSEY, AssIGNoE To NEW JEEsEY PATENT COMPANY, oE WEsT ORANGE, NEW JERSEY, A CORPORA- TION OF NEW JERSEY.

METHOD OE MAKING MbLDs vEOE SOUND-RECORDS.

To all 'whom it may concern: i

Beit known that I, THOMAS A. EDISON, a citizen of the United States, and a resident of Llewellyn Park, West Orange, in the county of Essexand State of New Jersey, have invented certain new. and' useful Improvements in Methods of Making Molds for Sound-Records, of which the following is a description. v

My invention relates to methods of making'molds for sound records, particularly those of the disk type. In forming these molds, it is common to coat the original wax record witha covering of graphite to renderits surface electro-conductive, then to place it in an electro-plating bath and deposit 4a thin layer of copper thereon by electrolysis.- The copper electrotype or matrixI thus vformed is then separated from the waxlike original record and backed u in any suitable way to give the same su cient rigidity for use as a' stamp or die to impress the record into the record material. lt'y has heretofore been common to secure the backing, which is commonly made of metal, to the electrotype or matrix by soldering the said parts together over substantially the whole of the contacting surfaces. This method of securing the matrix or electrotype to the backing is objectionable as in nearly every case the soldering is uneven so that an uneven surface is produced in the matrix and in the record formed therefrom when said parts are subjected to the great pressure necessary to impress the record into the plastic material from which the duplicates are to be formed. The unevenness of the record produced in this way is the cause of some of the noises which are emitted whenthe record is reproduced.

It'is the object of my invention to obviate the above named objection and to produce a mold which is strong and capable of producing an exact duplicate of the original sound record.

Broadly, my invention consists in` an im,- proved method of securing the matrix or electrotype to the backing in such a way as to obviate the necessity of soldering the whole of the two contactin surfaces thereof. This may be accomplis ed by finishing in any suitable Way the contacting surfaces of the electrotype or matrix and the backing so that by submitting the sameto pres- Specication of Letters Patent.

Patented Nov. 24, 1914i Appucauun'mea :une 1o, 1911.'l se'riei No. 632,366.

. sure, the .said parts may be caused to lie closely in engagement with each other, and thensecuring the same together at their edges. v

In vorder that my invention may bemore afully understood, attention is hereby div rected to the-accompanying drawings formlng. a part of this specification, and in which- .Figure 1 represents acentral vertical section of the original master record with the electro-deposited matrix thereon; Fig. 2 represents a similar View showing the matrix mounted upon a suitableA support or holder foruse during the finishing of the rear or yreverse surface thereof; Fig. 3 represents a similar View of a completed mold embodying my invention; and Fi represents a similar .view of a modi ed form of mold.

ln all of the views, like parts are designated by the same reference numerals.

Referring to the drawing, the numeral 1 represents the wax master record upon which the matrix 2 has been formed, as by electrolysis, in a copper bath. The outer surface of the matrix, as shown iin Fig.` 1, is more or less rough when removed from the bath. yAfter detaching the electrotype or matrix from the master, 4I provide .thev

same with a facing 3 of soft material, such as blotting paper` or the like, and secure the flange 2 .at the edge thereof upon a holder 4 in any suitable way," as by means of screws 5. n e

As shown in. Fig. 2, 'a bolt 6 is passed through alined 'openings in the center of the matrix 2, the facing 3, and the holder 4 and is provided with nuts 7, 7 whereby it is adapted to assist in clamping the matrix to the holder. VThe numeral 8 designates a Washer interposed between the bottom of ,the holder 4 and the upper nut 7. The matrix 2, having turned true and polished, the. matrix and the backing are superposed. with their finished surfaces in contact and are subjected to pressure to force them into firm engagement with each other. The ange 2 on the matrix is then removed, as oy cutting the Same away in a lathe, or in any other suitableyway, after which the edges of the matrix A'and backing are secured together. vlin vmy preferred construction, lt spin the edge of the electrotype or matrix over the edge of the backing and into the shallow groove or depression 10 in the backing; but

it is evident that the edges of thev matrix and backing may be secured to each other by. soldering or in any other suitable way.

In the modified form of my invention shown in Fig. 4, the matrix 22 and the backing 9 are secured together and to a supporting plate 1l by means of a ring l2 threaded on to the periphery of the plate 11 and provided with an annular Harige 13 overlying the edge of the matrix. Sockets 14 are .provided in the ring 12 for the insertion of pins or other suitable means for turning the said ring to loosen or tighten the same. A sleeve 15 provided with a ange 16 seated in a depression in the top of the matrix is threaded to the center of the backing and assists in securing the matrix in place. I prefer to make the backing 9 of steel and the platell of cast iron,

the contacting surfaces of these parts being ground true but not polished. The opposing faces of the matrix and backing are turned and polished as described above.

The polish and trueness of the opposing surfacesof the matrix andfbacking need not be as great as is'ne'cessary when the surfaces are directly-in contact with each other if a sheet 17. of tinfoil or other yielding material is laid between the opposing faces of the matrix and backing as shown in Fig. 4, such the vsame under material yielding under the molding pres- Sure and conforming readily to the slight irregularities in the 'said faces. This foil or l equivalent material should, however, be very thin preferably no thicker lthan about .005

of an inch in order to vprevent flowing of the high pressures used in molding records of the commonly employed plastic material. lt is evident that this f oil may be used in all forms of' my invention regardless of the particular method employed `for securing together the edges of the matrix and backing.

The numeral v1.8 designates a pin secured to the center of the mold and adapted to center the blank in be stamped.' A v While I have shown my invention as applied to 4disk records, it is evidentl appli cable to cylindrical records as we l. The finishing of the opposing surfaces of the 'matrix and backing may be accomplished 1n any suitable way and numerous modi y cations may be made in the method de# scribed without departing from the spirit of my invention.

I dol not claim herein my improved mold, the latter being claimed in another appliwhich the record is to idiaiia cation, Serial No. 866,437', filed October 13, 1914 as a division of this case.

What I claim as new and desire to secure by Letters Patent is as follows:

1. The method of making molds for sound records consisting in forming a matrix of the original record, truing or fnisliin the reverse or unmolded surface thereof, orming a backing with a finished surface adapted toclosely contact Vthe finished surface of the matrix, superposing the matrix and backing with their finished surfaces in contact, subjecting the superposed matrix and backing to pressure to force the same to lie 'in close engagement with each other, and

e backing to pressure to force the same to lie m` close engagement with each other, and

securing the same together only at their edges, substantially as described.

v3. The method of making molds for sound i records consisting in forming a metallic matrix of the original record, forming a back ing with a surface adapted to closely contact the rear surface of the matrix, superposing the matrix and backing with the said surfaces in contact and spinning the ed e of the matrix over the backing, substantially as described.

4. rl`he method of making molds for sound records consisting in forming a metallic matrix of the original record, truing or finishing the reverse or unmolded surface thereof, forming'a backing with a finished surface adapted to closely contact the finished surface of the matrlx, superposing the matrix and backing with the. finished surfaces in contact', sub]ecting the said parts to pressure to force the same to lie in close engagement with each other, and securing together the edges thereof, substantially as described.

' 5. The method of making molds for sound records consisting in forming a matrix of the original record, linishin the reverse or unmolded surface thereof, orming a backing with a finished surface having the same shape as the finished surface of the matrix,

ing the reverse or unmolded surface thereof, forming a backing with a surface adapted to closely contact the finished surface of the matrix, and with a groove or depression in the periphery thereof, superposing the matrix and backing, subjecting the said parts to pressure, and spinning the edge of the matrix over the backing into the said groove or depression, substantially as described.

7. The method of making molds for sound records consisting in forming a-metallic matrix of the original record, truing and polishingthe reverse or unmolded surface thereof, forming a backing With a true polished surface adapted to closely contact the nished surface of the matrix, superposing the matrix and backing with the polished surfaces in contact, subjecting thesaid parts to pressure, and securing the same together only at their edges, substantially as de-l scribed.

8. The method of making molds for sound records consisting in forming a metallic matrix of the original record, facing the matrix With a soft material, and securing the. same to a holder, truing and polishing the reverse or unmolded surface thereof, removing the matrix from the holder, forming a backing with a trued surface adapted to closely contact the trued surface of the matrix, superposing the' matrix and backing, subjecting the saidl parts to pressure, and securing the same together at their peripheries but not intermediate their peripheries and centers, substantially as described.

This specification signed and witnessed this 8th day of June 1911,

THos. A. EDISON.

Witnesses:

. FREDERICK BAorIMANN,

' ANNA ft. KLEHM. 

